org.apache.commons.collections4.functors
Class ConstantTransformer<I,O>

java.lang.Object
  extended by org.apache.commons.collections4.functors.ConstantTransformer<I,O>
All Implemented Interfaces:
Serializable, Transformer<I,O>

public class ConstantTransformer<I,O>
extends Object
implements Transformer<I,O>, Serializable

Transformer implementation that returns the same constant each time.

No check is made that the object is immutable. In general, only immutable objects should use the constant factory. Mutable objects should use the prototype factory.

Since:
3.0
Version:
$Id: ConstantTransformer.java 1479408 2013-05-05 22:15:05Z sebb $
See Also:
Serialized Form

Field Summary
static Transformer<Object,Object> NULL_INSTANCE
          Returns null each time
 
Constructor Summary
ConstantTransformer(O constantToReturn)
          Constructor that performs no validation.
 
Method Summary
static
<I,O> Transformer<I,O>
constantTransformer(O constantToReturn)
          Transformer method that performs validation.
 boolean equals(Object obj)
          
 O getConstant()
          Gets the constant.
 int hashCode()
          
static
<I,O> Transformer<I,O>
nullTransformer()
          Get a typed null instance.
 O transform(I input)
          Transforms the input by ignoring it and returning the stored constant instead.
 
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

NULL_INSTANCE

public static final Transformer<Object,Object> NULL_INSTANCE
Returns null each time

Constructor Detail

ConstantTransformer

public ConstantTransformer(O constantToReturn)
Constructor that performs no validation. Use constantTransformer if you want that.

Parameters:
constantToReturn - the constant to return each time
Method Detail

nullTransformer

public static <I,O> Transformer<I,O> nullTransformer()
Get a typed null instance.

Type Parameters:
I - the input type
O - the output type
Returns:
Transformer that always returns null.

constantTransformer

public static <I,O> Transformer<I,O> constantTransformer(O constantToReturn)
Transformer method that performs validation.

Type Parameters:
I - the input type
O - the output type
Parameters:
constantToReturn - the constant object to return each time in the factory
Returns:
the constant factory.

transform

public O transform(I input)
Transforms the input by ignoring it and returning the stored constant instead.

Specified by:
transform in interface Transformer<I,O>
Parameters:
input - the input object which is ignored
Returns:
the stored constant

getConstant

public O getConstant()
Gets the constant.

Returns:
the constant
Since:
3.1

equals

public boolean equals(Object obj)

Overrides:
equals in class Object

hashCode

public int hashCode()

Overrides:
hashCode in class Object


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